Current Mechanistic Understanding of Surface Reactions over Water-Splitting Photocatalysts

Solar water splitting for hydrogen generation over semiconductor photoelectrodes is a promising solution to the energy crisis and environmental issues. Because complex physical, chemical, and electrical processes are involved in solar energy conversion reactions, understanding the mechanisms is of great significance for the rational design of highly efficient solar water-splitting cells. This review describes the current mechanistic understanding of the adsorption of reactants, injection of charge carriers, and desorption of products during surface redox reactions. Variations of interfacial band-gap structures, the status of surface bonding, and the behavior of charge carriers in semiconductor photoelectrodes are discussed. This review could inspire further innovative work on understanding the mechanisms of solar water splitting.